You know, the over enthusiastic, always happy, never ruffled, good-natured, cheery, chirpy, model citizens? Whether you've consciously realized it or not, these individuals may be spreading their happiness in an epidemiological fashion to others. And, this has now been scientifically proven, people.
What, you ask, is the effect of the converse, Debbie Downer? The study, detailed in New Scientist, also states that dour sentiments spread slower than happiness.
So take stock... Your mood has a larger ripple effect on those around you than you know.